Harmonic selective signal for party telephone-lines



(No Model.)

J. A. LIGHTHIPE. HARMONIGV SELECTIVE SIGNAL FOR PARTY TELEPHONE LINES.

No. 550,982. Patented Dec. 10, 1895.

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JAMES A. LIGHTHIPE, OF SAN FRANCISCO, CALIFORNIA.

HARMONIC SELECTIVE SIGNAL FOR PARTYTELEPHONE-LINES.

SPECIFICATION forming part of Letters Patent No. 550,982, dated December 10, 1895.

Application filed June 24, 1895. Serial No. 563,861. (No model.)

To aZZ whom it may concern.-

Be it known that 1, JAMES A. LIGHTHIPE, a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented a certain new and useful Improvement in Harmonic Selective Signals for Party Telephone-Lines, (Case No. 1,) of which the following is a full, clear, concise, and exact description,reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to a harmonic selective signal apparatus for party telephone-lines, its object being to provide means whereby any one of a number of subscribers connected with a common or party telephone-line may be called by a selective signal sent from the central oflice.

In accordance with my invention a receiver in the form of a mechanically-vibrated reed is provided at each of the several sub-stations connected with the party-line, each of the reeds having a different and characteristic pitch, while at the central station the operator is provided with a number of transmitters adapted to throw upon the line pulsating or alternating currents of a pitch correspondingwith the pitch of any one of the receivers,

whereby the reed belonging to the particular receiver is thrown into vibration to ring a bell or actuate other signal, and thereby call the attention of the subscriber.

Referring to the accompanying drawings, Figure 1 is a diagram illustrating my invention in connection with two party-lines connected together at the central station. Fig. 2 is a modification of the transmitting apparatus at the central station.

The apparatus at the sub-stations C and B are connected with the limbs a a of a partyline extending to the central station and terminating in the line-springs a a of a springjack.

, At the central station I have indicated a usual form of individual-indicator b, in circuit with a battery 1), between contact-anvils b and b adapted to normally rest in contact with the line-springs a? and a respectively. At sub-station A the receiver 0 and transmitter 0 are included between the limb a of the line and contact-anvil 0 against which the telephone-hook c is adapted to rest when the telephone is removed therefrom, the telephone-hook being connected with the limb a of the line. When the receiver is hung up, the hook c rests upon a contact 0 connected through an electromagnet cl and condenser cl with the limb a. In front of the electromagnet cl is supported a reed (1 having a characteristic number of vibrations, the reed carrying upon its end a hammer (1 adapted in the movement of the reed to strike against the gongs (Z (1 The subscriber B is likewise provided with a telephone-receiver c and transmitter 0, connected between the limb a and the contact 0 against which the hook c is adapted to rest when the telephone is removedtherefrom. The electromagnet of the signaling device is in this instance connected directly between the two limbs a and a of the telephone-line, being included in circuit with the condenser e. A reed e havinga characteristic number of vibrations different from that of the reed C1 is supportedin front of the magnet e and carries upon its end a hammer e adapted to sound the gongs 6 I have shown a plug f inserted into the spring-jack at the central station, thus looping the operators cord-connectors into circuit with the line. A battery 9 hasone pole connected with the strand f of the cord-connectors, while the other pole is connected with anvils or contact-points h and '2', adapted to be engaged, respectively, by the levers of keys h and a" when depressed. The key h is connected through the electromagnet h with the strand f of the cord-connectors, while the key Q) is connected through the electromagnet t with the strand f. In front of the electromagnet h is mounted a reed 71 having a characteristic number of vibrations corresponding to the number of vibrations of the reed d at sub-station A. The reed h is electrically connected by the conductor 77, with the strand f while the stop h againstwhich the reed is adapted to strike in its vibration, is electrically connected by conductor b with the opposite side of the battery 9. When the gizing the magnet h thus causing the same to release reed 71 which falls back, opening the circuit between contact 7L5 and the reed and permitting another impulse to be sent through the magnet and out over the line. The reed 7L3 is thus vibrated at a rate dependent upon the characteristic vibration of which the reed is capable, while a corresponding number of impulses are sent through the electromagnets d and c at the substations. As the reed d is pitched to vibrate in harmony with the impulses thus sent over the line, the bell at sub-station A will be rung, while the bell at substation B will remain quiescent, since the number of vibrations is not in harmony with the pitch of the reed c The reed is adapted to vibrate at the same rate as the reed c at substation B, so that when the key 1" is depressed impulses'will be thrown upon the line having the number of vibrations of the reed c and in consequence the bell at sub-station B will be sounded.

Upon the right of Fig. 1 I have illustrated two a'dditionalsub-stations C and D, in which the electromagnets k and Z, respectively, of the signal devices are included between the limb m of the line and ground, while at r the central station the eleetromag-nets'o-and pot the transmitting devices and battery 9" are included between the strand f and ground, the circuit-connections being otherwise the same, so that the calling-currents are sent over the limb m of the telephone-line with a ground return instead of returning over the other limb of the metallic circuit, as shown upon the left. This arrangement of the call ing system is also applicable to grounded telephone-lines.

Suppose, for illustration, subscriber A is desirous of conversing with subscriber B. .IIc removes his telephone-receiver c from its hook, permitting the hook c to come in contact with anvil c and closing together the two limbs a a of the telephone-line "at the sub-station. The circuit of battery '11 is thus closed through indicator Z), calling cheat/tention of the operator, who inserts the plug f into the spring-jack and inquires as to the number of the called subscriber by bridging the telephone set between the two strand-sot the cord-conductors, the telephone set being omitted in the drawings, as it forms no part of the present invention. Learning that subscriber A desires to converse with sub energized andattracting the reed r scriber 13, she depresses the key i,thus throwing impulses upon the line adapted to vibrate the reed c and ring the bell of subscriber B. Should subscriber A desire to converse with subscriber C, she would depress key 0, thus vibrating the reed at substation C, while if connection were desired with subscriberD she would depress key 19, thus vibrating the reed Z at substation D.

In Fig. 2 I have illustrated an arrangement of the transmitting apparatus to be employed when it is not desired to connect the battery 9 directly in circuit with the telephone-line. In this instance the magnet is wound with two coils r and r, the windings being in opposite directions, so that when current traverses both windings the magnet remains neutral. The telephonedine sis connected with the secondary s of an induction-coil provided with two primary windings $283, one in circuit with each of the windings r 0". The winding s is connected directly to one pole of the battery 9, While the winding is connected with the reed W. The contact r against which the reed is adapted tostrilte,is conneeted directly to the pole oi the battery. Between the oppositepo-le cf the battery and the-windings 'r and r of the magnet is in eluded the keyt. When the keyt is depressed,

current from battery 9 flows through the Winding rof the magnet and the primary '5 of the transformer and thence to the opposite pole of the battery, the magnet being thus Assoon as the reed strikes the contact r circuit is closed through the winding 7" and the primary s of the transformer. Current thus simultaneously traverses the two windings :of the 'eleetromagnetand thetwo primary windings of r the transformer, which respectively neutralize one another, causing the magnet to release its reed r neutralizing thecurrent in the secondary of the transtormer. The release of the reed Wopens thecircuit through the windings *r and s and the reed is again contracted, the reed thus producing itscharacteristic vibration and causing impulse to be sent over the telephone-line.

Having described my invention, Whatl claim as new, anddesire to secure by Letters Patent, is

1. The combination with a telephone line connected with the secondary of a transformer, of a local circuit containing-a source of electricity and two parallel circuits or paths, an 'electronnagn'et provided with two opposedwindingsonewinding being included in each of said parallel paths, two primary windings torsaid transformer one included tent or Vibratory currents are produced in the telephone line 5 substantially as described.

2. The combination with a source of electricity of an electro-magnet provided with two opposed windings said windings being included in parallel paths of the circuit, a reed adapted to Vibrate in front of the pole of said electro-Inagnet, and contact points controlled by the vibration of said reed for intermittently opening and closing the cir- 1o cuit through one of said windings; substantially as and for the purpose set forth.

In witness whereof I hereunto subscribe my name this 15th day of June, A. D. 1895.

JAMES A. LIGHTHIPE. Witnesses:

F. O. MosEBAcH, CHAS. M. COLE. 

